Block-type heat exchanger



JQHANN LENDER ALSO KNOWN AS HANS UNDER ETAL May 9, 1967 3,318,375

BLOCK-TYPE BERT EXCHANGER 4 Sheets-Sheet 1 Filed Sept. 4, 1964 Fig.2

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ALSO KNOWN AS HANS UNDER ETAL BLOCK-TYPE HEAT EXCHANGER Filed Sept. 4, 1964 4 Sheets-Sheet 2 m/ Q My May 9, 1967 JOHANN LENDER ALSO KNOWN AS HANS UNDER ETAL BLOCK-TYPE HEAT EXCHANGE-R 4 Sheets-Sheet 5 Filed Sept. 4, 1964 Fig.6

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ALSO KNOWN As HANS LENDER ETAL BLOCK-TYPE HEAT EXCHANGER Filed Sept. 4, 1964 4 Sheets-Sheet 4 United States Patent BLOCK-TYPE HEAT EXCHANGER Johann Linder, also known as Hans Linder, Kreis Wertingen, near Augsburg, and Klaus Schmidt, Kreis Newburg (Danube), Germany, assignors to Siemens-Planiawerke Aktiengesellschaft fiir Kohlefabrikate, Meitingen, near Augsburg, Germany, a corporation of Germany Filed Sept. 4, 1964, Ser. No. 394,529

9 Claims. (Cl. 165-164) Our invention relates to devices for heat exchange between two media passing through respective groups of channels which extend parallel in a block structure, the channels of one group being of rounded cross-sectional shape and the channels of the other group being formed by slots of the block structure.

The known heat exchangers of this type are composed of a number of graphite plates which are individually provided with grooves and recesses and are joined together to form a block. Since the acid-resistant cement used as bonding medium, as a rule, is less heat resistant than the graphite material, the operability of these heat exchangers is decisively limited by the cement.

It is an object of our invention to devise a block-type heat exchanger which, for a given size, affords better operating properties, such as operation at higher temperatures, better efficiency or higher throughput.

Another, conjoint object is to simplify the production of block-type heat exchangers, and to increase their reliability and safety of performance.

Another object, akin to those mentioned, is to devise a block-type heat exchanger in which the high temperature resistance of the graphite, or other material employed for the block structure can be fully utilized, thus obviating the above-mentioned severe limitations.

A further object is to avoid the difiiculties and trouble heretofore often encountered by the fact that the materials of the above-mentioned plates and of the bonding cement have different thermal coefficients of expansion and thus lead to the occurrence of detrimental thermal tension.

Still another object of the invention is to provide a block-type heat exchanger device exhibiting a higher mechanical strength and a higher resistance to internal pressure stresses than obtainable with a multiplate device of the above-mentioned, known type, as well as improved resistance to corrosion and erosion.

To achieve these objects and in accordance with a feature of our invention, we form a heat exchanger block of a single piece of material which contains the above-mentioned two groups of channels for the respective media, the channels of one group being tubular, that is, having a rounded cross section fully enclosed within the block material, and the channels of the other group having a slot-shaped cross section which extends inwardly from the perimeter of the single-piece block and is open at the perimeter relative to the block.

A heat exchanger block according to the invention is preferably surrounded by a jacket with sufficient clearance to provide for a gap around the block so that the slotshaped channels communicate with the gap to be traversed by one of the media passing through respective inlets and outlets of the jacket.

According to a further feature of the invention, the efiicacy of the heat exchanger is further increased by subdividing the length of the individual slot-shaped channel by one or more partitions into a plurality of longitudinally sequential portions. The flowing medium is thus deflected by each portion outwardly in the direction toward the housing wall or jacket of the heat exchanger, and the flow of medium is subdivided into several portions. The condensate in each individual portion, collecting at one of the partitions, can freely drip off from that partition or it is flung from the partition against the jacket or housing wall where it drains along the inner surface to an outlet. Thus the condensate no longer reaches the next portion of the slot channels. When the slot channels are supplied with gaseous medium, for example steam for heating purposes, the medium is thus repeatedly liberated from the condensate at the partitions, and the heat transfer between the flowing medium and the material of the heat exchanger is improved.

This will be understood if one considers the following.

If condensate liquid, such as water, forms a film upon the inner wall of the individual slot channels and drains along the wall, it gradually increases its film thickness, so that the exchange of heat is impaired by the corresponding increase in heat transfer resistance. Consequently by eliminating or minimizing this phenomenon, the heat transfer value between the two channel groups can be appreciably increased. Assume, for example, that the single-piece block has a height of about three meters and that the slot channels along the block are subdivided by the above-mentioned partitions into portions of 0.4 m. Under these conditions, the heat transfer value between the two channel groups obtained during operation of the heat exchanger block is about three times higher than without subdivision by the partitions. If a condensation in form of drops or a mixed condensation instead of a condensate film occurs, a further increase in heat transfer value is obtainable, for example up to ten times the value observed when only film condensation takes place.

While reference is made in the foregoing to a singlepiece block containing the two channel groups, it will be understood that the total block structure of a heat exchanger may be subdivided transverse to its longitudinal direction into several subsidiary block units; this being tantamount to having several blocks according to the invention joined together in coaxial relation so that the two groups of channels in one block are aligned with the respective groups of channels in the adjacent block. This is often desirable for manufacturing reasons, particularly if the total block structure is to be of relatively great length, for example several meters. Such a composition of a heat exchanger from several single-piece blocks also facilitates repair and reconditioning work, because sometimes only individual block units need be exchanged.

The subdivision into individual blocks also has the advantage that the above-mentioned partitions in the slot channels can be formed more readily. That is, they can be positioned at those localities where adjacent blocks are joined with each other.

The above-mentioned and other objects, advantages and features of our invention, said features being set forth with particularity in the claim annexed hereto, will be apparent from and will be mentioned in, the following with reference to embodiments of heat exchanger devices according to the invention illustrated by Way of example on the accompanying drawing.

FIG. 1 is a cross section through a heat exchanger, the section being taken along line 5-8 in FIG. 2.

FIG. 2 shows a longitudinal section through the same heat exchanger, the section being taken along the line A-B in FIG. 1.

FIGS. 3 and 4 shows respective cross sections of two other embodiments involving a modification of the block shape and of the channels.

FIG. 5 shows still another embodiment of a heat exchanger device partly by a front view and partly in longitudinal section.

FIG. -6 shows in longitudinal section the junction location between two adjacent single-piece blocks in a heat exchanger for absorption processes.

FIG. 7 is a schematic and perspective view onto the lower channel block according to FIG. 6.

FIG. 8 shows in longitudinal section the junction location between two single-piece blocks with an intermediate sealing plate; and

FIG. 9 is a top view onto the plate according to FIG. 8.

The heat exchanger device shown in FIGS. 1 and 2 comprises a cylindrical channel block 2 of circular cross section consisting of industrial carbon such as artificial graphite, for example. The block 2 is enclosed within a jacket 1 of sheet steel. The block 2 ,is provided with a group of tubularchannels 3 having a round cross section for passing one of the heat exchanging media through the block, andis also provided with a group. of slot channels 4 for the other medium. The channels 3 of the first group extend in the same directionas the channels for the second group, namely parallel to the axis of the cylindrical block.

Between the cylindrical jacket 1 and the coaxial channel block 2 there remains a jacket space in the shape of a cylindrical gap 5 which connects all of the slot channels 4 with each other and forms a plenum passage for the medium flowing to all of the slot channels. The slot channels 4, seen in cross section (FIG. 1), are all directed radially toward the center axis of the channel block 2. The; tubular channels 3 of round cross section are located between the slot channels.

The entire channel block structure of the illustrated device may'consist of a single piece. In the embodiment according to FIGS. 1 and 2, however, the block structure is subdivided transverse to its length into three component blocks 2, 6 and 7, each consisting of a single piece of material. Despite such subdivision, the advantages of single-piece block structures, relative to the cross section within each block, are fully preserved. The component blocks 2, 6 and 7 are each'provided with channels 3 ,of round cross section of the same number and distribution, and they are so joined together that the channel openings of adjacent blocks register with each other Placed between the adjacent axial faces 8 and 9 of :respective blocks 6 and 7 is a marginal sealing gasket 10- munication with the one aligned channel of the adjacent block. However, the interspace 11 is not detrimental but provides for desired mixing of the quantities of the medium issuing from the tubular channels of one of the adjacent blocks. Also, providing the annularsealing gaskets and the interspace formed thereby, affords a very simple manner of joining adjacent blocks which generally satisfies all requirements.

The slot channels 4 do not extend over the entire length of the respective component blocks 2, 6 and 7 but have one end located in somewhat spaced relation from one axial face, for'example the axial face 9 of block 6, and extend only to the vicinity of the other axial face, for exampleface 12 of the same block 6. The depth of each slot channel 4 increases from one end of the slot toward the middle, and thence decreases toward the opposite end. Inthis manner, a partition is formed in each individual slot channel in the vvicinity of the junction with the adjacent block.

The jacket 1 is provided with a supply duct 14 near its upper end and an outletqduct 15 near its lower end. The ductsserve for passing one of the heat exchange media through the slot-shaped channels 4. An inletopening 16 and an outlet opening 17 for the other medium passing through the channels 3 of round cross section, are located in respective bell-shaped parts 16a and 17a at the upper and lower ends of the heat exchanger device. The bell parts are joined with the adjacent blocks 2 and 7 with interposed marginal sealing gaskets 16b and 17b, respectively, which extend around the ends of the tubular chan-' nels contained in the blocks 2 and 7.

The medium entering through inlet opening 16 passes through the individual tubular channels 3 and sequentially through blocks 2, 6 and 7 before it leaves the heat exchanger through the outlet opening 17 in the bell-shaped part 17a.

The individual component blocks 2, 4 and 7 and the two bell-shaped closure parts 16a and 17a are held together by means of tensioning rods 1c to 1i which are uniformly distributed over the periphery and pass through respective end plates 1a and 112.

Various advantages altordedby virtue of the invention Will be readily apparent from the above-described embodiment. Since the cross section of the single-piece blocks is not subdivided and since no cement is used at critical localities, the heat resistance of the block material can be fully utilized and any thermal tension as may be due to differences in thermal expansion of block material and cement is avoided. Dueto the fact that each single-piece block has a considerably higher mechanical strength than a structure composed of a multiplicity of cemented individual parts, the heat exchanger can be subjected to much higher pressures and possesses a higher resistance to corrosion. This applies particularly to heat exchange blocks made of carbon, preferably gasand liquid-tight artificial graphite.

The manufacture of heat exchanger devices according to the invention is particularly simple. The arrangement and shape of the channels makes it possible to first drill the tubular channels 3 into each single-piece block and then thereafter mill the slot channels into the perimetric region or to machine the slot channels in any other desired manner from the outside into the piece.

Since the slot channels are open toward the perimeter, they can be inspected from the outside over their entire extent. This permits repairing any faults in the slot-channel walls prior to assembling the single-piece block into the heat exchanger device, to make certain that the slot channels are reliably sealed from the tubular channels. The same possibility is afforded if a heat exchanger is to be repaired or reconditioned after a single-piece block is disassembled from the device.

The above-described heat exchanger device according to FIGS. 1 and 2 is applicable for example as an evaporator. This particular use will be described presently by way of example.

The liquid to be evaporated is supplied through the inlet opening 16 and rises in the tubular channels 14 in which it is heated and evaporated. The vapor leaves the heat exchanger through the outlet opening 17 and passes into a conduit (not illustrated) or the like. For heating the liquid, hot vapor, particularly steam, is passed through the inlet duct 14 into the jacket space 5 and thus also into the slot channels 4. The steam is cooled as it passes through the slot channels and may become partly condensed before the steam and any resulting condensate are discharged through the outlet duct 15.

Due to the illustrated design of the slot channels 4, the flow of steam largely occurs along the path indicated by arrows, this path being repeatedly deflected. As the steam enters into the uppermost component block 7, it penetrates into the slot channels 4 and when reaching the lower ends of these channels is deflected by the gradual slope of the partitions toward the cylindrical jacket 1. The same flow path is repeated in the next following component blocks.

If water condenses from the steam in the uppermost block 7, the condensate, as a rule, appears as a liquid film on the walls of the slot channels. Such condensate, however, is not passed into the next following block but is deflected together with the steam flow against the inner surface of the cylindrical jacket 1. At the edge of the partition formed by the shape of the slot channels 4 and/ or along the inner surface of the jacket 1, the condensate drips or drains downwardly, thus being prevented from entering into the next block. Consequently, the next block receives only steam, separate from the water condensed in the preceding block. The same applies to the following component blocks.

This performance constitutes an essential advantage in comparison with previous designs of block-type heat exchangers. As mentioned, if the condensate could run over the entire remaining length of the channel block, the heat from the steam would have to pass through the liquid film which increases in thickness in the downward direction, and the heat transfer coefiicient would continuously increase from the top toward the bottom of the heat exchanger. However, since according to the invention the individual slot channels are subdivided by one or more partitions, the condensate forming in each channel portion is eliminated from the further flow of steam and any liquid film of condensate on the slot walls is not continuously thickened but commences to newly form behind each partition, beginning with zero thickness. This leads to a very considerable increase of the average heat transfer coefiicient and thus-for given dimensionsto a considerable increase in efliciency.

In an embodiment built and used in practice, it has been found advisable to keep the height of the individual slot channel portions at approximately 0.4 m., relating to a device composed of several component blocks.

Among other uses for a heat exchanger device according to FIGS 1 and 2 is its application for heating a liquid, for example etching liquid, to be used in an etching bath. The following example relates to such use.

Etching liquid consisting of sulfuric acid is supplied at a temperature of about 20 C. through the inlet opening 16 and passes through the tubular channels 3. Steam for heating the etching liquid is passed through the inlet duct 14 into the slot channels 4. The steam is supplied at a pressure of 6 atmospheres above ambient and at a temperature of about 165 C. The etching liquid is thus heated by heat exchange between the two groups of channels, for example up to an outlet temperature of about 65 C. The steam, as it passes through the slot channels, is colled and forms condensate water which is separated from slot portion to portion as described in the foregoing. The residual steam and the condensate leave the heat exchanger through the outlet duct 15.

The heated etching liquid is supplied for example directly to an etching tank (not illustrated) in which the etchant bath has an operating temperature of approximately 40 to 45 C. A pump can be used for circulating the etching liquid continuously from the etching trough to the heat exchanger and back to the etching trough.

By virtue of the single-piece channel block or the abovedescribed assembly of single-piece channel blocks, the heating steam, or generally one or the other medium or both, can be supplied into the channel block at a higher pressure than applicable if the channel block or the individual component blocks are made of several parts cemented together to form the channels entirely or partially between each other. This is also a reason for the fact that a heat exchanger according to the invention affords a considerably higher efficiency and improved operability, relative to given exchanger dimensions.

Heat exchangers of the type described are applicable for a great variety of other purposes, for example also for distilling HCl gas from hydrochloric acid. The hydrochloric acid, particularly in concentrated form, is supplied through the inlet opening 16 to the tubular channels 3. It passes upwardly through the channels 3 while being heated by the heating medium, particularly steam, supplied in the same direction or preferably in counterflow through the slot channels 4 at approximately 6 atmospheres above ambient pressure. The hydrochloric acid is thus heated to approximately 127 C. The evolving hydrogen chloride gas leaves the heat exchanger through the outlet Opening 17.

FIG. 3 shows an arrangement of the channels different from that of FIG. 1. According to FIG. 3, the slot channels, here denoted by 18a, are arranged in subgroups of three channels each. The center planes of the slot channels 18a in each subgroup are parallel to each other within the block 18. This permits machining the slot channels of each subgroup by a single cutting operation. Within the individual subgroup, the two outer channels have a smaller depth than the middle channel. It will be noted that in some similarity thereto the depth of the slot channels is alternately small and large in the embodiment shown in FIGS. 1 and 2. In all other respects the embodiment according to FIG. 3 may be identical with that of FIGS. 1 and 2. The tubular channels 18b are accommodated between the slot channels 18a in the distribution apparent from FIG. 3.

FIG. 4 shows a' cross section which in principle is similar to that of FIGS. 1 and 3 except for a. different cross-sectional shape of the block 19 and the arrangement of the channels. The channel block 19 has a generally square cross section with bevelled edges so as to constitute an octagon. The slot channels 19a are parallel to each other and extend into the block from two opposite sides. This has the same advantages as mentioned above with reference to FIG. 3. The tubular channels 1% are arranged in rows between and outside of the slot channels.

While the component blocks 2, 6 and 7 in the embodiment of FIGS. 1 and 2 are mounted within a single cylindrical jacket 1, the heat exchanger shown in FIG. 5 possesses for each individual component block a separate cylindrical jacket 21 with its own supply duct 22 and outlet duct 23, and each jacket is provided with flanges 24 and 25 at the axial ends thereof. Each individual block-and-jacket unit constitutes a modula subassembly, so that a heat exchanger of any desired length can be composed by joining a corresponding number of such units. For this purpose, the supply and inlet ducts are to be connected with each other. For example, the outlet duct 23 and the inlet duct 26 for the slot channels 29a and 20'a of sequential units 20 and 20 are shown joined with each other by a U-shaped conduit 27. The tubular channels 201) and 20'!) are connected with each other by joining the component blocks 20 and 20 at their adjacent axial sides in somewhat spaced relation to each other with the aid of a ring-shaped sealing gasket 28. The adjacent units are preferably joined in such a mutual position that the tubular channels 20b and 20b are in alignment with each other. Since the mutually adjacent axial sides of the blocks and the peripheral region in the junction region is freely visible from the outside, the annular gaskets between the channel blocks can be checked during operation, this being apparent in FIG. 5 with respect to the annular gaskets 28 and 29.

Among the various purposes for which heat exchangers according to the invention are applicable is their use for cooling processes. This will be exemplified by the following description of the embodiment shown in FIG. 5. The flow directions indicated in FIG. 5 by arrows correspond to this particular use, although the device is also applicable for many other purposes.

The cooling medium is entered into the inlet duct of the lowermost unit, this duct corresponding to the one denoted by 22 of the unit shown entirely in section (FIG. 5). The cooling medium enters into the slot channels of the lowermost unit and leaves it through the uppermost duct corresponding to the one denoted by 23 in FIG. 5.

I Located in the cylindrical gap between the jacket 21 and thesingle-piece block 20. is a deflector ring 20C at the height of the plane S-S denoting the cross-sectional center planeof the block. The deflector ring 20C serves to deflect the cooling medium into the slotchannels so that it will predominantly pass only through these channels in order to provide for good heat transfer conditions between the cooling medium and the medium passing through the tubular channels;

When the-heat exchanger according to FIG. is used, for example, to'cool hydrochloric acid, azeotropic hydrochloric acid at about 127 C. may be passed downwardly through the tubular channels where it is cooled by coolant flowing upwardly through the slot channels. The coolant may consist of water at about to C. .or brine of about 15 to --20 C; The azeotropic hydrochloric acid leaves the heat exchanger at a temperature of about 40 C., for example.

Heat exchangers according to the invention are further applicable for heat-exchange processes in which the group of tubular channels is subdivided into subgroups with respectively separate inlets and outlets, in such a manner that the different subgroups can be connected in series and the particular medium passesrepeatedly through the total length of the channelblock for heat exchange.

Heat exchangers according to the invention may also be used for performing absorption processes in the tubular channels. For example, a gas may be passed from be caused to drain from above through the same channels in order to fully or partially absorb the ascendinggas.

The flow directions of gas and liquid just assumed, maybe opposed to each other (counterfiow principle) or they. may have the same direction (uniflow principle). This also applies analogously to the two channel groups. That is, the respective media passing through the two channel groups may travel in uniflow or counterflow.

When a heat exchanger according to the invention is to'be used for performing an absorption process, it is advisable to employ supplemental auxiliary means as exemplified in FIGS. 6 and 7 described presently.

Relative to FIGS. 6 and 7 it is assumed that the channel structure is composed of several component blocks. Of these only the blocks and 31 are partially shown in FIG. 6. The tubular channels contained in the blocks ars denoted 'by 32 and 33 respectively. The slot channels are indicated at 30a in FIG. 7.

Placed upon each of the channels 32in block 30 is a distributor crown 34. Each crown has lateral inlet slots 35." The crowns 35 do not touch each other but leave a plenum interspace designated by 36. The component blocks and 41 are jointed together in such a manner that the tubular channels in one block are aligned with those of the otherblock. Each individual tubular channel of the upper block terminates above the lower block with an internally conical foot (FIG. 6) which freely surrounds the distributor crown of the adjacent tubular channel and terminates somewhatabove the axial face of the adjacent lowerchannel block.

As mentioned, when the heat exchanger is employed as an absorber, the tubular channels are downwardly traversed by liquid, for example water, whereas the gas to'be absorbed, or the gas mixture to be entirely or partially absorbed passesupwardly through the same channels.

The tubular channel 33 whose-lower portion is illustrated in FIG. 6, conducts on its inner wall a liquid film which constitutes the liquid which is to be enriched with the ascending gas being absorbed. This liquid film, coming from above, is schematically represented by anarrow 37. Theliquid film and the. liquid films issuing from the other tubular channels pass into the plenum space 36. Thence the liquid, when reaching a given level, flows through the inlet slots of the distributor crowns into the tubular channel of-the next, lower block, for example 2 K. through the distributor crown 34, fully illustrated in FIG. 6, into the tubular channel 32.

Each individual distributor crown has several, preferably uniformly distributed inlet slots. For simplicity only four such inlet slots are shown on the drawing and are denoted by 35 with respect to crown 34. As a rule, however, it is preferable to provide a considerably larger number of inlet slots, for example eight, twelve, sixteen or more, so that the liquid passing into the individual lower tubular channels is uniformly distributed over the entire inner surface of the channel. This is one of the essential purposes of the distributor crowns. In other words, it is desired that the individual channels be internally wetted uniformly by the liquid because the optimum of absorption is achieved when the available surfaces are fully utilized for spreading the absorbing liquid. The uniform'spreading of the liquid also prevents that certain areas on the inner surfaces of the tubular channels may remain dry or only slightly wetted so that precipitations may become firmly lodged.

The plenum interspace 36 between the two component channel blocks, in conjuction with the limited vertical depth of the inlet slots in the distributor crowns which enforces some accumulation of the absorption liquid in the interspace, has the effect that the quantities of liquid issuing from the upper channel block become mixed with each other in the interspace so that the respective concentrations are fully or at least partially equalized. As a consequence, the tubular channels of the next lower channel block are supplied with an absorption liquid of uniform concentration.

The interspace 36 is limited toward the outside by a ring-shaped sealing gasket 38 which is preferably seated in a groove in each axial end face of the block. The thickness of the sealing gasket 38 is sufficient to provide for the height of the plenum space required for accommodating the distributor crowns between the adjacent blocks.

The embodiment of the heat exchanger according to the invention illustrated in FIG. 8 is essentially similar to that described above with reference to FIGS. 1 and 2. The channel structure is divided into several component blocks. However, the partitions in the slot channels are not formed by the corresponding shape of the channels in the individual blocks. The slot channels rather extend, generally, at uniform depth, throughout the entire length of the individual channel block. In order to form the partitions, a sealing plate is inserted between each two adjacent channel blocks. In the region of the tubular channels, the plate has openings of the same diameters as the respective tubular channel and in registry therewith so that the tubular channels of one block communicate with the openings of the respective aligned channels of the adjacent 'block. In the region of the slot channels, however, the plate does not have an opening so that it separates the slot channels of the respective blocks from each other and thereby forms partitions at the junction location. Thesepar-titions serve the same purpose as those described above with reference to FIGS. 1, 2 and length. A sealing plate .46 is inserted between their adjacent front faces of the blocks 40 and 43 and has openings 47 through which the mutually aligned tubular channels 41 and 44 communicate, The top view of the sealing plate 46 shown in FIG. 9 shows the distribution of the openings 47.

At the localities of the slot channels 42, 45 the sealing plate 46 does not have openings but forms a partition for deflecting the flowing medium from the slot channels and forming an edge from which any condensate will drip ofif.

The advantages of single-piece channel blocks or a coaxial assembly of such blocks, are also realized in cases where the above-mentioned partitions in the slot channels are entirely or partly omitted. This is the case particularly if the medium used for heat transfer has such a high tempertaure and/ or is otherwise of such constitution, that a condensate will not occur in the slot channels or will occur only in negligible quantities.

In cases where partitions in the individual slot channels are desired, they may also be made of separate parts and then inserted into the channel block. For example, the individual partition may be given the shape of a wedge whose thin portion, extending transverse to the longitudinal direction of a slot channel, is directed outwardly with respect to the block, whereas the areas extending away from the edge of the wedge are preferably concave and merge with the bottom of the slot channels.

While in the illustrated embodiment the slot channels are shown to have parallel slot walls, the cross section of the slot channels may also be V-shaped, widening toward the perimeter in order to facilitate the flow of medium into and out of the slot channels.

The channel blocks as well as the bell-shaped cover plates are preferably made of graphite, especially if the heat exchanger is to be acid-resistant. It is preferable to employ for this purpose a particularly prepared graphite, namely a graphite impregnated with synthetic resin subsequently hardened to render the graphite highly gasand liquid-tight. Such graphite material is available in commerce under the trademark Diabon.

When employing heat exchangers according to the invention at temperatures above 200 C., it is advisable to make the channel blocks of graphite which is rendered gasand liquid-tight at such high temperatures by embedding secondary carbon in the graphite mass, such prepared carbon being likewise known and available in commerce.

To those skilled in the art it will be obvious from a study of this disclosure that our invention permits of various modifications and can be given embodiments other than those illustrated and described herein, without departing from the essential features of the invention and within the scope of the claims annexed hereto.

We claim:

1. A device for heat exchange between two media, comprising a block formed of a single piece of material and having two groups of channels for said respective media, both channel groups extending in the same longitudinal direction, the channels of one group having a round cross section surrounded by said material, the channels of the other group having a slot-shaped cross section which extends inwardly from the perimeter of said block and is open at said perimeter, partition means for subdividing said longitudinal channels of said other group into lengthwise sequential portions, said partition means being adapted to deflect a flow of one of the media through said channels of said other group, and a jacket surrounding said block and having respective inlet and outlet ducts for one of said media, said jacket and block forming between each other a gap space extending around said block and communicating with said slot-shaped channels.

2. In a heat exchanger device according to claim 1, said respective inlet and outlet ducts of said jacket being located near the two axial end sides of said single-piece block.

3. A device for heat exchange between two media, comprising a cylindrical block formed of a single piece of material and having therein two groups of channels for said respective media, said channels extending parallel to the axis of said block, the channels of one group having a round cross section surrounded by said material, the channels of the other group having a slot-shaped cross section which extends inwardly from the perimeter of said 1o block and is open at said perimeter, partition means for subdividing said longitudinal channels of said other group into lengthwise sequential portions, said partition means being adapted to deflect a flow of one of the media through said channels of said other group, and a cylindrical jacket surrounding said block with radial clearance so as to form a cylindrical interspace communicating with said slot shaped channels, said jacket having inlet and outlet means near the axial end faces of said block for one of said media, and ring shaped partition means surrounding said block in said interspace for guiding said one medium through said slot-shaped channels.

4. A device for heat exchange between two media, comprising a cylindrical block formed of a single piece of material and having therein two groups of channels for said respective media, said channels extending parallel to the axis of said block, the channels of one group having a round cross section surrounded by said material and extending from one axial end of said block to the other, the channels of the other group having a slot-shaped cross section which extends inwardly from the perimeter of said block and is open at said perimeter, said latter channels :having a shorter length than said block and terminating in spaced relation from said respective axial ends, partitions extending transverse of said slot-shaped channels and subdividing them into lengthwise sequential portions, and a jacket surrounding said block and having respective inlet and outlet ducts for one of said media, said jacket and block forming between each other a gap space extending around said block and communicating with said slot-shaped channels.

5. A device for heat exchange between two media, comprising a plurality of coaxially aligned blocks joined with each other, each block having two parallel groups of channels aligned with the respective channel groups of each adjacent block, each of said blocks being formed of a single piece of material, the channels of one group in each block having a round cross section surrounded by said material, the channels of the other group having a slot-shaped cross section which extends inwardly from the perimeter of said block and is open at said perimeter, said slot-shaped channels in each of said blocks being shorter than the block and having respective channel ends spaced from the axial ends of the block, the depth of said slot-shaped channels increasing from each channel and toward the middle, whereby each two adjacent ones of said blocks form a partition between their respective mutually aligned slot-shaped channels, and a jacket structure surrounding said blocks and having respective inlet and outlet ducts for one of said media, said jacket structure forming a gap space extending around said blocks and communicating with said slot-shaped channels.

6. A heat exchanger device according to claim 5, comprising an annular sealing member between two adjacent ones of said blocks, said sealing member surrounding the channel openings of said one group and forming between said two blocks a plenum space through which the channels of said one group in both of said blocks communicate with one another.

7. In a heat exchanger device according to claim 5, said jacket structure being transversely subdivided intoindividual jackets, each of said jackets being joined with one of said respective blocks to form a unit therewith, and each jacket having flange means joining it with an adjacent one of said jackets.

8. In a heat exchanger device according to claim 5 for a use requiring the passage of gaseous medium and also the downward flow of liquid through said channels of said first group, said blocks being aligned in an upright direction and having a plenum space between each two adjacent blocks, a distributor crown disposed on top of the lower block in each plenum space around each channel opening of said one group and having a lurality of lateral overflow slots through which liquid may drain from said space onto the channel walls in the lower block,

the upper one of said two blocks having respective. downward extensions in which its channels of said one group terminate, said extensions being annular and extending coaxially about said respective crowns for passing liquid into said plenum space.

9. In a heat exchanger device according to claim 5, said slot channels extending along the entire length of each block and having substantially uniform depth, a sealing plate interposed between two adjacent ones of said blocks and having respective openings through which said channels of said one group in one block communicate with the respective aligned channels of the adjacent other block, said plate forming a partition between the respective aligned slot channels of said two blocks.

References Cited by the Examiner UNITED STATES PATENTS 2,519,845 8/1950 Mojonnier et al. 165-174 X 2,707,096 4/1955 Koopmans 165165 2,821,369 1/1958 Hilliard 165164 X 2,887,304 5/1959 Hilliard 165165 FOREIGN PATENTS 202,355 7/1956 Australia. 1,867,931 2/1963 Germany.

ROBERT A. OLEARY, Primary Examiner.

M. A. ANTONAKAS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,318,375 May 9, 1967 Johann Linder, also known as Hans Linder, et a1: It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below In the heading to the printed specification, between lines 8 and 9, insert the following:

Claims priority, application Germany, Sept. 6, 1963, S 87,146

Signed and sealed this 14th day of January 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

1. A DEVICE FOR HEAT EXCHANGE BETWEEN TWO MEDIA, COMPRISING A BLOCK FORMED OF A SINGLE PIECE OF MATERIAL AND HAVING TWO GROUPS OF CHANNELS FOR SAID RESPECTIVE MEDIA, BOTH CHANNEL GROUPS EXTENDING IN THE SAME LONGITUDINAL DIRECTION, THE CHANNELS OF ONE GROUP HAVING A ROUND CROSS SECTION SURROUNDED BY SAID MATERIAL, THE CHANNELS OF THE OTHER GROUP HAVING A SLOT-SHAPED CROSS SECTION WHICH EXTENDS INWARDLY FROM THE PERIMETER OF SAID BLOCK AND IS OPEN AT SAID PERIMETER, PARTITION MEANS FOR SUBDIVIDING SAID LONGITUDINAL CHANNELS OF SAID OTHER GROUP INTO LENGTHWISE SEQUENTIAL PORTIONS, SAID PARTITION MEANS BEING ADAPTED TO DEFLECT A FLOW OF ONE OF THE MEDIA 